Finally tonight, remembering the man who made us laugh in comedies from animal house, to caddyshack, "Ghostbusters," Harold Ramis had a hand in them all. John donvan remembers the man who perfected the comedy of the hapless adventurer. Reporter: Kinda nerdy, but kinda subversive at the same time. This is big, peter. This is very big. Reporter: That was Harold Ramis in "Ghostbuisters." It was kind of his trademark. And why so many of the films he worked in have really stuck in the culture. "Caddyshack," which he directed about a nerdy subversive. "Animal house," which he co-wrote about subversive nerds. Comedies that were smarter than goofball. Dark at times, but always with a light left on. His "Groundhog day," for example, sort of nightmare, but inside a kind of snowball. Ramis came up through Chicago's legendary second city comedy troupe, serving for a time as head writer, the same generation as the original "Saturday night live" cast, with whom he worked with in several movies -- chevy chase, in "National lampoon's vacation," with that scene on the highway. Work that inspired a younger generation, like writer and director, Judd apatow, who actually interviewed Ramis for his high school radio station, and then, years later, cast him in his own huge hit, "Knocked up," and five years ago in "Year one." It was the last movie Ramis would direct. He died early this morning in Chicago, just short of 70 years. Comedy is radical in spirit. It challenges people's assumptions and expectations. We always felt that we part of that great tradition. Reporter: A guy who battled ghosts, he leaves behind the spirit of what he was -- a nerd. A subversive. A funny man. John donvan X, ABC news, Washington.

This transcript has been automatically generated and may not be 100% accurate.

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